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Linux 2.6.17.7
[linux/fpc-iii.git] / fs / fat / fatent.c
blobab171ea8e869b2cc9da6369abad3a83c970d2a96
1 /*
2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
4 */
5
6 #include <linux/module.h>
7 #include <linux/fs.h>
8 #include <linux/msdos_fs.h>
9
10 struct fatent_operations {
11 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
12 void (*ent_set_ptr)(struct fat_entry *, int);
13 int (*ent_bread)(struct super_block *, struct fat_entry *,
14 int, sector_t);
15 int (*ent_get)(struct fat_entry *);
16 void (*ent_put)(struct fat_entry *, int);
17 int (*ent_next)(struct fat_entry *);
18 };
19
20 static void fat12_ent_blocknr(struct super_block *sb, int entry,
21 int *offset, sector_t *blocknr)
22 {
23 struct msdos_sb_info *sbi = MSDOS_SB(sb);
24 int bytes = entry + (entry >> 1);
25 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
26 *offset = bytes & (sb->s_blocksize - 1);
27 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
28 }
29
30 static void fat_ent_blocknr(struct super_block *sb, int entry,
31 int *offset, sector_t *blocknr)
32 {
33 struct msdos_sb_info *sbi = MSDOS_SB(sb);
34 int bytes = (entry << sbi->fatent_shift);
35 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
36 *offset = bytes & (sb->s_blocksize - 1);
37 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
38 }
39
40 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
41 {
42 struct buffer_head **bhs = fatent->bhs;
43 if (fatent->nr_bhs == 1) {
44 WARN_ON(offset >= (bhs[0]->b_size - 1));
45 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
46 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
47 } else {
48 WARN_ON(offset != (bhs[0]->b_size - 1));
49 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
50 fatent->u.ent12_p[1] = bhs[1]->b_data;
51 }
52 }
53
54 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
55 {
56 WARN_ON(offset & (2 - 1));
57 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
58 }
59
60 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
61 {
62 WARN_ON(offset & (4 - 1));
63 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
64 }
65
66 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
67 int offset, sector_t blocknr)
68 {
69 struct buffer_head **bhs = fatent->bhs;
70
71 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
72 bhs[0] = sb_bread(sb, blocknr);
73 if (!bhs[0])
74 goto err;
75
76 if ((offset + 1) < sb->s_blocksize)
77 fatent->nr_bhs = 1;
78 else {
79 /* This entry is block boundary, it needs the next block */
80 blocknr++;
81 bhs[1] = sb_bread(sb, blocknr);
82 if (!bhs[1])
83 goto err_brelse;
84 fatent->nr_bhs = 2;
85 }
86 fat12_ent_set_ptr(fatent, offset);
87 return 0;
88
89 err_brelse:
90 brelse(bhs[0]);
91 err:
92 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
93 (unsigned long long)blocknr);
94 return -EIO;
95 }
96
97 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
98 int offset, sector_t blocknr)
99 {
100 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
101
102 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
103 fatent->bhs[0] = sb_bread(sb, blocknr);
104 if (!fatent->bhs[0]) {
105 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
106 (unsigned long long)blocknr);
107 return -EIO;
108 }
109 fatent->nr_bhs = 1;
110 ops->ent_set_ptr(fatent, offset);
111 return 0;
112 }
113
114 static int fat12_ent_get(struct fat_entry *fatent)
115 {
116 u8 **ent12_p = fatent->u.ent12_p;
117 int next;
118
119 if (fatent->entry & 1)
120 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
121 else
122 next = (*ent12_p[1] << 8) | *ent12_p[0];
123 next &= 0x0fff;
124 if (next >= BAD_FAT12)
125 next = FAT_ENT_EOF;
126 return next;
127 }
128
129 static int fat16_ent_get(struct fat_entry *fatent)
130 {
131 int next = le16_to_cpu(*fatent->u.ent16_p);
132 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
133 if (next >= BAD_FAT16)
134 next = FAT_ENT_EOF;
135 return next;
136 }
137
138 static int fat32_ent_get(struct fat_entry *fatent)
139 {
140 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
141 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
142 if (next >= BAD_FAT32)
143 next = FAT_ENT_EOF;
144 return next;
145 }
146
147 static void fat12_ent_put(struct fat_entry *fatent, int new)
148 {
149 u8 **ent12_p = fatent->u.ent12_p;
150
151 if (new == FAT_ENT_EOF)
152 new = EOF_FAT12;
153
154 if (fatent->entry & 1) {
155 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
156 *ent12_p[1] = new >> 4;
157 } else {
158 *ent12_p[0] = new & 0xff;
159 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
160 }
161
162 mark_buffer_dirty(fatent->bhs[0]);
163 if (fatent->nr_bhs == 2)
164 mark_buffer_dirty(fatent->bhs[1]);
165 }
166
167 static void fat16_ent_put(struct fat_entry *fatent, int new)
168 {
169 if (new == FAT_ENT_EOF)
170 new = EOF_FAT16;
171
172 *fatent->u.ent16_p = cpu_to_le16(new);
173 mark_buffer_dirty(fatent->bhs[0]);
174 }
175
176 static void fat32_ent_put(struct fat_entry *fatent, int new)
177 {
178 if (new == FAT_ENT_EOF)
179 new = EOF_FAT32;
180
181 WARN_ON(new & 0xf0000000);
182 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
183 *fatent->u.ent32_p = cpu_to_le32(new);
184 mark_buffer_dirty(fatent->bhs[0]);
185 }
186
187 static int fat12_ent_next(struct fat_entry *fatent)
188 {
189 u8 **ent12_p = fatent->u.ent12_p;
190 struct buffer_head **bhs = fatent->bhs;
191 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
192
193 fatent->entry++;
194 if (fatent->nr_bhs == 1) {
195 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
196 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
197 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
198 ent12_p[0] = nextp - 1;
199 ent12_p[1] = nextp;
200 return 1;
201 }
202 } else {
203 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
204 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
205 ent12_p[0] = nextp - 1;
206 ent12_p[1] = nextp;
207 brelse(bhs[0]);
208 bhs[0] = bhs[1];
209 fatent->nr_bhs = 1;
210 return 1;
211 }
212 ent12_p[0] = NULL;
213 ent12_p[1] = NULL;
214 return 0;
215 }
216
217 static int fat16_ent_next(struct fat_entry *fatent)
218 {
219 const struct buffer_head *bh = fatent->bhs[0];
220 fatent->entry++;
221 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
222 fatent->u.ent16_p++;
223 return 1;
224 }
225 fatent->u.ent16_p = NULL;
226 return 0;
227 }
228
229 static int fat32_ent_next(struct fat_entry *fatent)
230 {
231 const struct buffer_head *bh = fatent->bhs[0];
232 fatent->entry++;
233 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
234 fatent->u.ent32_p++;
235 return 1;
236 }
237 fatent->u.ent32_p = NULL;
238 return 0;
239 }
240
241 static struct fatent_operations fat12_ops = {
242 .ent_blocknr = fat12_ent_blocknr,
243 .ent_set_ptr = fat12_ent_set_ptr,
244 .ent_bread = fat12_ent_bread,
245 .ent_get = fat12_ent_get,
246 .ent_put = fat12_ent_put,
247 .ent_next = fat12_ent_next,
248 };
249
250 static struct fatent_operations fat16_ops = {
251 .ent_blocknr = fat_ent_blocknr,
252 .ent_set_ptr = fat16_ent_set_ptr,
253 .ent_bread = fat_ent_bread,
254 .ent_get = fat16_ent_get,
255 .ent_put = fat16_ent_put,
256 .ent_next = fat16_ent_next,
257 };
258
259 static struct fatent_operations fat32_ops = {
260 .ent_blocknr = fat_ent_blocknr,
261 .ent_set_ptr = fat32_ent_set_ptr,
262 .ent_bread = fat_ent_bread,
263 .ent_get = fat32_ent_get,
264 .ent_put = fat32_ent_put,
265 .ent_next = fat32_ent_next,
266 };
267
268 static inline void lock_fat(struct msdos_sb_info *sbi)
269 {
270 mutex_lock(&sbi->fat_lock);
271 }
272
273 static inline void unlock_fat(struct msdos_sb_info *sbi)
274 {
275 mutex_unlock(&sbi->fat_lock);
276 }
277
278 void fat_ent_access_init(struct super_block *sb)
279 {
280 struct msdos_sb_info *sbi = MSDOS_SB(sb);
281
282 mutex_init(&sbi->fat_lock);
283
284 switch (sbi->fat_bits) {
285 case 32:
286 sbi->fatent_shift = 2;
287 sbi->fatent_ops = &fat32_ops;
288 break;
289 case 16:
290 sbi->fatent_shift = 1;
291 sbi->fatent_ops = &fat16_ops;
292 break;
293 case 12:
294 sbi->fatent_shift = -1;
295 sbi->fatent_ops = &fat12_ops;
296 break;
297 }
298 }
299
300 static inline int fat_ent_update_ptr(struct super_block *sb,
301 struct fat_entry *fatent,
302 int offset, sector_t blocknr)
303 {
304 struct msdos_sb_info *sbi = MSDOS_SB(sb);
305 struct fatent_operations *ops = sbi->fatent_ops;
306 struct buffer_head **bhs = fatent->bhs;
307
308 /* Is this fatent's blocks including this entry? */
309 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
310 return 0;
311 /* Does this entry need the next block? */
312 if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
313 if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1))
314 return 0;
315 }
316 ops->ent_set_ptr(fatent, offset);
317 return 1;
318 }
319
320 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
321 {
322 struct super_block *sb = inode->i_sb;
323 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
324 struct fatent_operations *ops = sbi->fatent_ops;
325 int err, offset;
326 sector_t blocknr;
327
328 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
329 fatent_brelse(fatent);
330 fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
331 return -EIO;
332 }
333
334 fatent_set_entry(fatent, entry);
335 ops->ent_blocknr(sb, entry, &offset, &blocknr);
336
337 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
338 fatent_brelse(fatent);
339 err = ops->ent_bread(sb, fatent, offset, blocknr);
340 if (err)
341 return err;
342 }
343 return ops->ent_get(fatent);
344 }
345
346 /* FIXME: We can write the blocks as more big chunk. */
347 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
348 int nr_bhs)
349 {
350 struct msdos_sb_info *sbi = MSDOS_SB(sb);
351 struct buffer_head *c_bh;
352 int err, n, copy;
353
354 err = 0;
355 for (copy = 1; copy < sbi->fats; copy++) {
356 sector_t backup_fat = sbi->fat_length * copy;
357
358 for (n = 0; n < nr_bhs; n++) {
359 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
360 if (!c_bh) {
361 err = -ENOMEM;
362 goto error;
363 }
364 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
365 set_buffer_uptodate(c_bh);
366 mark_buffer_dirty(c_bh);
367 if (sb->s_flags & MS_SYNCHRONOUS)
368 err = sync_dirty_buffer(c_bh);
369 brelse(c_bh);
370 if (err)
371 goto error;
372 }
373 }
374 error:
375 return err;
376 }
377
378 int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
379 int new, int wait)
380 {
381 struct super_block *sb = inode->i_sb;
382 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
383 int err;
384
385 ops->ent_put(fatent, new);
386 if (wait) {
387 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
388 if (err)
389 return err;
390 }
391 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
392 }
393
394 static inline int fat_ent_next(struct msdos_sb_info *sbi,
395 struct fat_entry *fatent)
396 {
397 if (sbi->fatent_ops->ent_next(fatent)) {
398 if (fatent->entry < sbi->max_cluster)
399 return 1;
400 }
401 return 0;
402 }
403
404 static inline int fat_ent_read_block(struct super_block *sb,
405 struct fat_entry *fatent)
406 {
407 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
408 sector_t blocknr;
409 int offset;
410
411 fatent_brelse(fatent);
412 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
413 return ops->ent_bread(sb, fatent, offset, blocknr);
414 }
415
416 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
417 struct fat_entry *fatent)
418 {
419 int n, i;
420
421 for (n = 0; n < fatent->nr_bhs; n++) {
422 for (i = 0; i < *nr_bhs; i++) {
423 if (fatent->bhs[n] == bhs[i])
424 break;
425 }
426 if (i == *nr_bhs) {
427 get_bh(fatent->bhs[n]);
428 bhs[i] = fatent->bhs[n];
429 (*nr_bhs)++;
430 }
431 }
432 }
433
434 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
435 {
436 struct super_block *sb = inode->i_sb;
437 struct msdos_sb_info *sbi = MSDOS_SB(sb);
438 struct fatent_operations *ops = sbi->fatent_ops;
439 struct fat_entry fatent, prev_ent;
440 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
441 int i, count, err, nr_bhs, idx_clus;
442
443 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
444
445 lock_fat(sbi);
446 if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) {
447 unlock_fat(sbi);
448 return -ENOSPC;
449 }
450
451 err = nr_bhs = idx_clus = 0;
452 count = FAT_START_ENT;
453 fatent_init(&prev_ent);
454 fatent_init(&fatent);
455 fatent_set_entry(&fatent, sbi->prev_free + 1);
456 while (count < sbi->max_cluster) {
457 if (fatent.entry >= sbi->max_cluster)
458 fatent.entry = FAT_START_ENT;
459 fatent_set_entry(&fatent, fatent.entry);
460 err = fat_ent_read_block(sb, &fatent);
461 if (err)
462 goto out;
463
464 /* Find the free entries in a block */
465 do {
466 if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
467 int entry = fatent.entry;
468
469 /* make the cluster chain */
470 ops->ent_put(&fatent, FAT_ENT_EOF);
471 if (prev_ent.nr_bhs)
472 ops->ent_put(&prev_ent, entry);
473
474 fat_collect_bhs(bhs, &nr_bhs, &fatent);
475
476 sbi->prev_free = entry;
477 if (sbi->free_clusters != -1)
478 sbi->free_clusters--;
479 sb->s_dirt = 1;
480
481 cluster[idx_clus] = entry;
482 idx_clus++;
483 if (idx_clus == nr_cluster)
484 goto out;
485
486 /*
487 * fat_collect_bhs() gets ref-count of bhs,
488 * so we can still use the prev_ent.
489 */
490 prev_ent = fatent;
491 }
492 count++;
493 if (count == sbi->max_cluster)
494 break;
495 } while (fat_ent_next(sbi, &fatent));
496 }
497
498 /* Couldn't allocate the free entries */
499 sbi->free_clusters = 0;
500 sb->s_dirt = 1;
501 err = -ENOSPC;
502
503 out:
504 unlock_fat(sbi);
505 fatent_brelse(&fatent);
506 if (!err) {
507 if (inode_needs_sync(inode))
508 err = fat_sync_bhs(bhs, nr_bhs);
509 if (!err)
510 err = fat_mirror_bhs(sb, bhs, nr_bhs);
511 }
512 for (i = 0; i < nr_bhs; i++)
513 brelse(bhs[i]);
514
515 if (err && idx_clus)
516 fat_free_clusters(inode, cluster[0]);
517
518 return err;
519 }
520
521 int fat_free_clusters(struct inode *inode, int cluster)
522 {
523 struct super_block *sb = inode->i_sb;
524 struct msdos_sb_info *sbi = MSDOS_SB(sb);
525 struct fatent_operations *ops = sbi->fatent_ops;
526 struct fat_entry fatent;
527 struct buffer_head *bhs[MAX_BUF_PER_PAGE];
528 int i, err, nr_bhs;
529
530 nr_bhs = 0;
531 fatent_init(&fatent);
532 lock_fat(sbi);
533 do {
534 cluster = fat_ent_read(inode, &fatent, cluster);
535 if (cluster < 0) {
536 err = cluster;
537 goto error;
538 } else if (cluster == FAT_ENT_FREE) {
539 fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
540 __FUNCTION__);
541 err = -EIO;
542 goto error;
543 }
544
545 ops->ent_put(&fatent, FAT_ENT_FREE);
546 if (sbi->free_clusters != -1) {
547 sbi->free_clusters++;
548 sb->s_dirt = 1;
549 }
550
551 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
552 if (sb->s_flags & MS_SYNCHRONOUS) {
553 err = fat_sync_bhs(bhs, nr_bhs);
554 if (err)
555 goto error;
556 }
557 err = fat_mirror_bhs(sb, bhs, nr_bhs);
558 if (err)
559 goto error;
560 for (i = 0; i < nr_bhs; i++)
561 brelse(bhs[i]);
562 nr_bhs = 0;
563 }
564 fat_collect_bhs(bhs, &nr_bhs, &fatent);
565 } while (cluster != FAT_ENT_EOF);
566
567 if (sb->s_flags & MS_SYNCHRONOUS) {
568 err = fat_sync_bhs(bhs, nr_bhs);
569 if (err)
570 goto error;
571 }
572 err = fat_mirror_bhs(sb, bhs, nr_bhs);
573 error:
574 fatent_brelse(&fatent);
575 for (i = 0; i < nr_bhs; i++)
576 brelse(bhs[i]);
577 unlock_fat(sbi);
578
579 fat_clusters_flush(sb);
580
581 return err;
582 }
583
584 EXPORT_SYMBOL_GPL(fat_free_clusters);
585
586 int fat_count_free_clusters(struct super_block *sb)
587 {
588 struct msdos_sb_info *sbi = MSDOS_SB(sb);
589 struct fatent_operations *ops = sbi->fatent_ops;
590 struct fat_entry fatent;
591 int err = 0, free;
592
593 lock_fat(sbi);
594 if (sbi->free_clusters != -1)
595 goto out;
596
597 free = 0;
598 fatent_init(&fatent);
599 fatent_set_entry(&fatent, FAT_START_ENT);
600 while (fatent.entry < sbi->max_cluster) {
601 err = fat_ent_read_block(sb, &fatent);
602 if (err)
603 goto out;
604
605 do {
606 if (ops->ent_get(&fatent) == FAT_ENT_FREE)
607 free++;
608 } while (fat_ent_next(sbi, &fatent));
609 }
610 sbi->free_clusters = free;
611 sb->s_dirt = 1;
612 fatent_brelse(&fatent);
613 out:
614 unlock_fat(sbi);
615 return err;
616 }
Linux with added FPC-III support